// WGS84转GCJ02
function transformLat(x, y) {
    var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
    ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
    ret += (20.0 * Math.sin(y * Math.PI) + 40.0 * Math.sin(y / 3.0 * Math.PI)) * 2.0 / 3.0;
    ret += (160.0 * Math.sin(y / 12.0 * Math.PI) + 320 * Math.sin(y * Math.PI / 30.0)) * 2.0 / 3.0;
    return ret;
  }
  
  function transformLng(x, y) {
    var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
    ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
    ret += (20.0 * Math.sin(x * Math.PI) + 40.0 * Math.sin(x / 3.0 * Math.PI)) * 2.0 / 3.0;
    ret += (150.0 * Math.sin(x / 12.0 * Math.PI) + 300.0 * Math.sin(x / 30.0 * Math.PI)) * 2.0 / 3.0;
    return ret;
  }
  
  function outOfChina(lng, lat) {
    return (lng < 72.004 || lng > 137.8347) || (lat < 0.8293 || lat > 55.8271);
  }
  
  function wgs84togcj02(lng, lat) {
    var a = 6378245.0; // 地球长半轴
    var ee = 0.00669342162296594323; // 扁率
    if (outOfChina(lng, lat)) {
      return [lng, lat];
    }
    var dLat = transformLat(lng - 105.0, lat - 35.0);
    var dLng = transformLng(lng - 105.0, lat - 35.0);
    var radLat = lat / 180.0 * Math.PI;
    var magic = Math.sin(radLat);
    magic = 1 - ee * magic * magic;
    var sqrtMagic = Math.sqrt(magic);
    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * Math.PI);
    dLng = (dLng * 180.0) / (a / sqrtMagic * Math.cos(radLat) * Math.PI);
    var mgLat = lat + dLat;
    var mgLng = lng + dLng;
    return [mgLng, mgLat];
  }
  
  // 导出方法
  export {
    transformLat,
    transformLng,
    outOfChina,
    wgs84togcj02
  };